Unit 1: Leaning Aim B Flashcards
What is the internet? What does it do?
A global network of interconnected computers
It allows data to be exchanged between computers and devices
What is difference between the internet and the World Wide Web?
- The internet is the technology, the hardware
The World Wide Web is the content, the web pages, the data
What does a server do?
Runs special software to serve other computers
Give 4 examples of servers
File servers
Print servers
Web servers
Email servers
What is a client?
- A computer/device that uses services provided by a server
- The computer/device you use to access the internet is a client
What is a router?
Devices which ‘route’ (direct) traffic (data) through a network
- They are intelligent and will try to find the best routes
What are cables/connections?
The connection between all of the hardware {router,client,server,etc.}
Examples of cables?
Telephone lines, fibre and cables etc
What is the backbone?
A ‘big’ cable (most of the time a fibre) which connects a large number of devices
What does ISP stand for?
Internet Service Provider
What does ISP do?
Allows connection to the internet for a client
Why do we need ISP?
Too expensive to connect directly to internet so it gives an easy way for connection
What kind of network does the ISP allow some connection to?
It can either be a home network or a business network
Is there a limit to how many clients can have access?
No It can be one client or a network of clients
What can the ISP also provide?
Additional services such as website development and technical support.
What is the problem with additional services that the IP provides?
It is usually for an additional fee
What do network diagrams do?
They show how pieces of technology connect together
What does PoP stand for?
Point of Presence
What is PoP?
It is an access point to the internet
How do PoPs benefit an ISP?
An ISP may have several PoPs to allow good access to the internet
What does NAP stand for?
Network Access Point
What is NAP?
Its where different networks interconnect onto the internet
What are the three connection methods to the internet?
Wireless
Broadband
Dial-up
What is the wireless connection method?
Where you connect without wires
What is the broadband connection method?
Its a wired connection through a broadband supplier
What is the dial-up connection method?
Its a wired connection using a modem and telephone lines
Whats are some advantages for using a wireless connection method? 2
- You are not fixed to a stationary computer
- It can be used wherever wireless internet is available
Whats an advantage for using a broadband connection method? Exam-style
There is a better reception than dial-up
Exam-style-Higher bandwidth and faster downloads so that movies can be watched without interruption/less buffering
Whats an advantage for using a dial-up connection method?
You can use existing telephone lines,giving connection where broadband is not available
What are some disadvantages for using a wireless connection method? 3
- Needs to have wireless internet available
- Can be less secure than wired
- Tends to be slower than wired
What are some disadvantages for using a dial-up connection method? 3
- Older technology can give poor reception
- Conversation between digital and analogue signals can cause errors
- Usually slower than other methods
Whats a disadvantage for using a broadband connection method?
Wired, so has to be used on a stationary computer
What is bandwidth?
It is how the speed of sections of the internet is measured.
What does bandwidth describe?
It describes how much capacity {space} there is to carry data
What are the units for bandwidth?
Bits per second
The number of bits of data that can be transmitted in one second
What does it mean to have a high bandwidth?
It means more information can be moved during that time , therefore giving a faster internet connection and a higher transmission rate
What are protocols?
A set of rules that allow computer systems to connect with different systems to transfer data
What does TCP stand for?
Transmission Control Protocol
What are two steps TCP does?
- It takes data from user’s application
- It then passes it to the IP
The opposite happens at the other end of the transmission
What does IP stand for?
Internet Protocol
What are 3 steps the IP does?
- Takes data from TCP
- Organises it into packets
- Routes it across the network and puts the packet back into the correct order at the other end of the transmission
What does FTP stand for?
File Transfer Protocol
What is FTP?What is it used for?
It is the protocol which allows files to be transferred between two computers or devices
It is used to download or upload large files to a server
What is the World Wide Web?
The content on the internet
Examples of World Wide Web-content on the internet
Web pages
Files and other data
Why does the World Wide Web work?
Because of hyperlinks
What do hyperlinks do?
They connect web pages together
What happens when a hyperlink is clicked on?
A user is taken to another page on a website or a different website
Where are websites stored?
On website servers
What happens to the web browser when a user accesses a website through a web browser?
It is temporarily downloaded onto their computor
What is the web servers job to do when a user tries to access a web page?
To deliver the web page requested.
How are web pages accessed?
Through web browsers
What do web browsers do?
They allow a user to enter a URL and view a web page
What does HTML stand for?
Hyper Text Markup Language
What is HTML?
The language used to create web pages
What is HTML made up of?
Tags
What are tags usually grouped in?
Pairs
What are pairs of tags called?
HTML elements
How are open tags written?
< >
How are closed tags written?
The same as open tag but it has a / so it looks like this: />
What does URL stand for?
Uniform Resource Locator
What are the main three parts of an URL?
Protocols
Path
Domain name
Why is there a protocol in an URL?
It tells the browser what to do with the URL
Why is there a domain name in an URL?
It is the name of the website
Why is there a path in an URL?
It points to a specific web page
In this URL [ http://www.edexcel.com/subjects/BTEC-IT/ ] what part is:
a} protocol
b} domain name
c} path
a} http://
b} edexcel.com
c} subjects/BTEC-IT/
What does HTTP stand for?
HyperText Transfer Protocol
What does HTTP allow us to do?
Request web pages and download them to our computers
When does a we page start with ftp://?
When the web page has uploads and downloads
What do most web pages start with in their URLs?
http://
What are search engines?
Websites which allow users to find data on the internet
Give two examples of search engines?
Google.com
Bing.com
Explain what happens when a user searches something up. {4}
1} The user enters keywords into the search engine
2} The search engine searches its indexed database of web pages on the internet
3} The results are displayed in order of popularity with sponsored links at the top
4} All the time web spiders are moving around the internet looking for new web pages. When they find it they log it in an indexed database
What are sponsored links? {Example}
Links that will appear at the top of the screen if that companies link pays money for it
The more money the company pays, the more likely it is to appear in the searches.
{E.g a company which pays less money will have their link come up if it includes key words like ‘durham’ or ‘exotic’ which is very specific unless they payed more the link would come up for every search including the phrase ‘pet shop’}
What is another name for web spider?
Web crawler
What are web spiders/web crawlers?What do they do?
Small automated programs{bots}
They automatically move around the internet looking for new web pages all the time without any human involvement
What is email?
A method of communicating by sending messages through an email server
Where generally are emails sent from and where are they sent into?
A senders outbox and in a recipient’s inbox
The sender and recipient of an email message {do/do not} have to be online at the same time
Do not
What are the benefits of email? {7}
- You can send files as attachments
- You can send messages to multiple people at the same time
- It is faster than post
- You can forward messages you have received to other people
- You can record contacts in an adress book so you can access them quickly
- Webmail providers tend to store emails on a remote provider, meaning that you can access them quickly
- You can set up distribution lists to quickly send to multiple people at the same time
What are the limitations of email?
- Viruses can be spread through emails
- Phishing emails may be recieved {asking for private information}
- Employees in a business may spend time on personal email at work
- Emails may be intercepted and read by hackers
- Spam can be irritating, waste time and take up space in an inbox
What system is email known as?
Store and Forward system
What 3 communication protocols are used when sending and receiving emails?
POP3
IMAP
SMTP
What does SMTP stand for?
Simple Mail Transfer Protocol
What does POP3 stand for?
Post Office Protocol 3
What does IMAP stand for?
Internet Message Access Protocol
What does SMTP do?
Pushes the mail from the server to the client
What does POP3 do?
Pulls the mailfrom the server to the client when requested
What is IMAP used for?
Web mail
Explain the ‘store and forward system’
Email is sent by the sender client to the email server. It is ‘stored’ there until the recipient client requests access and then the email is ‘forwarded’ to their computer
What are three wired transmission methods?
UTP/STP
Coaxial
Fibre Optic
What is UTP?
What is STP?
Cables made up of pairs of copper wires twisted together. STP is a shielded cable which has a protective layer around the copper wires (under the plastic coating) to protect the data from interference
What is coaxial?
Solid copper wire with thick shielding
What does UTP stand for?
Unshielded Twisted Pair
What does STP stand for?
Shielded Twisted Pair
What is fibre optic and what does it use to do what job?
Glass or plastic cables which ussse light to transmit data
What are the advantages of using UTP/STP?(3)
- Interference is lessened due to the twisting
- Cheaper than other methods
- Reliable
What is an advantage of using coaxil?
It is reliable
What are the advantages of using fibre optic? (3)
- Fast
- Used over long distances
- Little interference
What are the disadvantages of using UTP/STP?(4)
- Slow
- Low capacity
- Used over short distances
- Susceptible to noise, which means the data can be interfered with if near another digital device or signal
What are the disadvantages of using coaxil?(5)
- Slow
- Low capacity
- Used over short distances
- Thick and physically inflexible
- Susceptible to noise, which means the data can be interfered with if near another digital device or signal
What are the disadvantages of using fibre optic? (2)
- Expensive
- Complex to install (needs a specialist)
What is an example of using UTP/STP transmission method?
Connecting computers to a network backbone
What is an example of using coaxial transmission method?
TV networks e.g TV to aerial
What is an example of using fibre optic transmission method?
Backbone of a network
What are the three wirelesss transmission methods?
- Infrared
- Microwave
- Satellite
What does infrared transmission methods use to do what?
- infrared light
- to transfer data
What does microwave transmission methods use to do what?
- short wavelengths (invisible to human eye)
- to transmit data
What does satellite transmission methods use to do what?
- satellites in space
- to relay data between different points of earth
What is an advantage of infrared transmission methods?
It is reliable
What is an advantage of microwave transmission methods?
Good for long distances
What is an advantage of satellite transmission methods?
Good for very long distances
What are the disadvantages of infrared transmission methods?
- Short range
- Devices must be in line of sight
- Can suffer from interference
What is a disadvantage of microwave transmission methods?
Can suffer from interference from other devices
What is a disadvantage of satellite transmission methods?
Very expensive
Give an example of infrared transmission methods
Television remote
Give an example of microwave transmission methods
Bluetooth
Give an example of satellite transmission methods
Global communication systems
Devices using wireless networking need what?
NIC - Network Interface Card
What is a NIC?
A hardware in a device which allows it to recieve wireless signals
The NIC will connect to what?
Network Access Points (NAPs)
What is Packet switching?Where used?
The process of data being broken down before being sent through a network and then reassembled at the other end
-On the internet
What is the role of error control bits?
these check that the packets have been reassembled correctly
What is payload?
Data
What is a source address?
Where the data comes from
What is a destination address?
Where the data is going
What is the role of packet identification?
It identifies the packet and knows how to reassemble them
What are CODECS used for in VoIP?
They are used to encode and decode data
What is the method of VoIP packet switching? (5)
1) The sender’s computer records a message using a webcam or microphone
2) The message is converted into digital data
3) This is then broken into packets
4) The packets are sent across the internet
5) The received computer receives the packets assembles them and decodes the data so it can be seen and heard
What are the advantages of packet switching?
- Sends data across a network efficiently
- It means big files which would otherwise clog up the network, can be sent whole
- Allows efficient movement of data through a network because small packets can choose different routes through a network
- There is a security benefit because if a packet is intercepted, the
What are the advantages of packet switching?
- Sends data across a network efficiently
- It means big files which would otherwise clog up the network, can be sent whole
- Allows efficient movement of data through a network because small packets can choose different routes through a network
- There is a security benefit because if a packet is intercepted, the hacker will only have one part of the file
What is a disadvantage of packet switching?
If one or more packets are lost or corrupted during transmission, the whole file will not be received correctly
What are three types of transmission modes?
- Simplex
- Half-duplex
- Full duplex
What direction does the signal go in simplex transmission mode?
Signals go in one direction at a time
What direction does the signal go in half-duplex transmission mode?
Signals go in both directions at the same time
What direction does the signal go in full-duplex transmission mode?
Signals go in both directions but the devices don’t transmit at the same time
What are two general transmission modes?
Serial
Parallel
How is data transferred in serial transmission modes?
Bits of data are transferred one at a time over a wire
How is data transferred in parallel transmission modes?
Bits of data are transferred simultaneously over a wire - a whole byte can be transferred at the same time
What is a benefit of serial transmission modes?
Good over long distances
What is a benefit of parallel transmission modes?
Faster because more bits are transferred per second
What is a limitation of serial transmission modes?
Complex because data has to be broken individual bits
What is a limitation of parallel transmission modes?
Shorter distance max 5 metres
What is a database?
A collection of data
Where is a set of data stored?
In a table
What is a record?
A row in a table that stores data about a single item
What is a field?
Categories that columns in a table store
What must each table in a database have?
Primary Key
What is a Primary Key?
A unique piece of data which identifies one record
To connect tables together another table should have what?
Foreign Key
What is a Foreign Key?
It is the primary key in a different table and creates a relationship
What are the 4 main data types used in databases?
Text
Number
Date/Time
Boolean
What is text?
Characters such as letters, numbers and symbols
